Yep, this is a persistent issue in the game. Nope, there are not any policies that change it. You create a Kingdom and find that your not the King, your just a puppet at the whims of your vassals and/or you actually somehow created a democracy without realizing it. It is a huge issue to me honestly. Hopefully they will decide to make a Rules decision absolute or someone will create a mod to do it.
Also, as far as I understand it, this is a balancing mechanism in a game or I should say wars are at the very least. The whole system is designed to make sure that the status quo is kept in any and all circumstances and it will get worse as you manage to expand your Kingdoms power. The more powerful you get the more your lords want to be in war and the more the other factions want to fight you. By the time you reach end game, you will be fighting every faction in perpetual war and no matter how good or bad your doing in any particular war, there will be no support to end the war ever.
I am facing this right now. I have a huge kingdom with 27 actual clans, no one can stop me yet it has turned out to be one of the most frustrating gameplay loops I have ever experienced. I am at war with nearly every faction, my lords support peace with none of them and I am finding that while I might be making progress in one area of the map, I lose the same amount of progress in another part. I guess I am slowly winning over all because I am exploiting the catch and release mechanic to make all enemy lords love me then recruiting them in time of war and getting them to bring all their fiefs with them but I feel frustrated because I have to bounce all over the map and constantly take back the castles and towns I lost while I was off fighting a war against another faction.
I know that this is designed to make sure I am being challenged as a player but I also feel like the end goal of any single player game is that the player is supposed to win and a system designed to be challenging just to be challenging rather than realistic is just frustrating. Also another part that frustrated me was why everyone was fighting only me. For example I don't even share a border with Vlandia and I am currently engaged in a very hard fought and highly contested war with both Battania and the Western Empire yet Vlandia has it hard for me. How about instead of challenging me with having to fight all factions, that Vlandia instead decides to go to war with Battania or the Western Empire and challenges me by growing their kingdom to the same size as mine while Battania and Western Empire are dealing with me??
Anyway, I don't like frustration for frustrations sake and that is all the constant wars are just frustrating. Also, ideally I don't want all factions being equal for the entire game, instead I want it to eventually be just 2 or 3 large faction vying for supremacy. Of course this is why I argue that snowballing isn't something that should have been eliminated because the ultimate goal of this game is conquering the world. The only snowballing I wanted to see fixed was the fact it was always the Khuziats that were snowballing. Honestly, I think we ended up with a worse game when they "balanced" it so that no faction can really manage to ever get superiority over another.